1. Field of the Invention
The present invention relates to a toner dispersing mechanism, which is mounted to an image forming apparatus such as an electrophotographic copier, a printer, and a facsimile, for dispersing toner replenished from a toner storage container such as a hopper and a container into a developing device.
2. Description of Related Art
Conventionally, for the facilitation of maintenance, a predetermined amount of toner is filled in advance into the developing device mounted to the image forming apparatus, and the developing device itself is replaced when the toner is depleted. However, the developing device cannot be frequently replaced from an economic viewpoint, and a toner capacity of the developing device is inevitably increased for performing image formation on many sheets to some extent. Thus, the above-mentioned developing device is difficult to achieve downsizing. Therefore, in order to achieve the downsizing of the developing device, there has been proposed a developing device of a type, to which toner is supplied from outside.
In the developing device of the toner supply type, a lump of toner is sometimes replenished into the developing device when toner fluidity is reduced owing to use environments, and the like. Thus, there is such a risk that the mixing property between the lump of toner and developer existing in the developing device is deteriorated and a developer thin layer formed on a developing roller is disturbed, with the result that image failures such as an image density unevenness and fogging may occur.
As counter measures, there have been proposed various technologies for suppressing occurrence of the image failures by preceding dispersion of the toner which is to be replenished into the developing device, through uses of a bristle brush roller and a sponge roller. For example, as disclosed in the first and second related arts, there has been known a developing device in which a toner replenishing brush is arranged between a toner hopper and the developing device. Further, as disclosed in the third related art, there has been known a developing device in which a sponge-like toner replenishing roller and a charging brush roller for preventing clogging of the toner replenishing roller are arranged between the toner hopper and the developing device.
However, there are such risks that bristle loss may occur when the bristle brush roller is used as the toner dispersing member as in the first and second related arts, and sponge tear-off may occur when the sponge roller is used as in the third related art. In those cases, there is a problem in that waste of a torn-off sponge and lost bristles may enter the developing device to be caught in a gap between a developing roller and a regulating blade (developer regulating portion), thereby generating an image with vertical white streaks.